1. Field of the Invention
The present invention relates to data transmission, and more particularly to a device and a method for transmitting data, wherein data is transmitted considering a packet processing calculation amount of a receiving side terminal when compressing the data and then transmitting them by the packet.
2. Description of the Related Art
With the development of mobile communication systems and integrated circuits, a variety of portable electronic terminals i.e., portable terminals, have been developed and produced. Typical examples of such portable terminals include a mobile communication terminal, a PMP (Portable Multimedia Player), a PSP (Play Station Portable), a PNP (Portable Navigation Player) and the like. Generally, portable terminals provide a multimedia function emphasizing user's entertainment functions such as moving image reproduction, music file reproduction, a game function and the like. In order to provide the multimedia function, portable terminals typically download and store multimedia data through an external data transmission device or communication system.
In general, the portable terminals download multimedia data transmitted in accordance with a real-time compression method when downloading the multimedia data. In the real-time compression method, a device for transmitting data compresses multimedia data files to be transmitted in real time and then sequentially transmits data using transmission packets. However, the multimedia data may have a partially different compression rate depending on a characteristic of data even within one multimedia data file. On this account, transmission packets with compression rates different from one another are transmitted to a receiving side terminal in the real-time compression method. If a receiving terminal receives transmission packets, it restores their compression to store them in a predetermined storage area. At this time, since the compression rates of the transmission packets are not identical with one another, the amount of data processing calculations of a receiving terminal controller, which are required when processing the transmission packets, is not also uniform. That is, in a case where transmission packets with a high compression rate are processed, the amount of data processing calculations of the receiving terminal controller increases and in a case where transmission packets with a low compression rate are processed, the amount of data processing calculations of the receiving terminal controller decreases.
Accordingly, problems may be encountered when the amount of data processing calculations increases to a degree at which the receiving terminal controller loads the maximum amount of data processing calculations and, at the same time, another minimum data processing calculation is also required. This will be described in FIG. 1 which is a graph illustrating a compression entropy degree of packets sequentially transmitted and a packet processing calculation amount for each packet in a receiving terminal according to conventional methods art.
Referring to FIG. 1, packets 1 to 8 transmitted from a device 19 have various compression entropies. The compression entropy is proportional to the compression rate of data contained in the packets. An amount of data processing calculations required by a portable terminal 20 receiving the aforementioned packets is shown. It can be seen that each data calculation amount in a row of calculation amounts corresponding to each packet in a row of entropies is proportional to the compression entropy of each of the packets. Numerals in brackets inside the packets denote a compression entropy degree and an amount of data processing calculations, respectively. As such, a data transmission method in accordance with conventional real-time data compression methods causes the controller of the portable terminal 20 to operate inefficiently.
Moreover, in a case of a portable terminal, there is a structural limitation in that its external size should be minimized and there is a limitation on processing performance of a controller provided according thereto. On this account, in a case where large-capacity multimedia data is downloaded and stored in accordance with the aforementioned real-time data compression method, a case may more frequently occur in which the required amount of calculations may meet or exceed a maximum amount of possible data processing calculations in the controller of the portable terminals. Accordingly, there is a problem in that processing time is delayed and excess power may be consumed.